Amylose fractionation from rice starch
1988
Panorjit Tanyamongkolpong
Amylose content in rice starch was 24 %. The optimum conditions for amylose fractionation were obtained by mixing 11 % magnesium sulfate solution with rice starch at a ratio of 20 : 1 (volume by weight); autoclaving the mixture at 125 deg. Celsius under a pressure of 1.5 kg/cm2 for 45 minutes; centrifuging at 9,000 rpm to separate amylose and amylopectin, and drying at 80 deg. Celsius. The yield in the amylose fraction was 37.6 % and this contained 42 % amylose. The yield in the amylopectin fraction was 23.3 % and this contained 16 % amylose as a residue. The rheological properties of the fractionated amylose were also investigated by adding the fractionated amylose to rice starch and letting them form a gel. It was found that the more amylose added, the greater the gel strength. Noodles made from the fractionated amylose and rice starch showed high stability of pulling resistance using an Instron Universal Testing Instrument. The pulling resistance of amylose edible film was also tested with this instrument while the shearing resistance of the film was tested using a TMI Elmendorf Tear Tester. It was found the amylose edible film gave higher values than amylopectin edible film and rice starch edible film.
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